1,258 research outputs found

    Simulating 0+1 Dimensional Quantum Gravity on Quantum Computers: Mini-Superspace Quantum Cosmology and the World Line Approach in Quantum Field Theory

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    Quantum computers are a promising candidate to radically expand computational science through increased computing power and more effective algorithms. In particular quantum computing could have a tremendous impact in the field of quantum cosmology. The goal of quantum cosmology is to describe the evolution of the Universe through the Wheeler-DeWitt equation or path integral methods without having to first formulate a full theory of quantum gravity. The quantum computer provides an advantage in this endeavor because it can perform path integrals in Lorentzian space and does not require constructing contour integrations in Euclidean gravity. Also quantum computers can provide advantages in systems with fermions which are difficult to analyze on classical computers. In this study, we first employed classical computational methods to analyze a Friedmann-Robertson-Walker mini-superspace with a scalar field and visualize the calculated wave function of the Universe for a variety of different values of the spatial curvature and cosmological constant. We them used IBM's Quantum Information Science Kit Python library and the variational quantum eigensolver to study the same systems on a quantum computer. The framework can also be extended to the world line approach to quantum field theory.Comment: 5 pages, 4 figure

    Large Area Crop Inventory Experiment (LACIE). Second-generation sampling strategy evaluation report

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    The author has identified the following significant results. The stratification procedure in the new sampling strategy for LACIE included: (1) correlation test results indicating that an agrophysical stratum may be homogeneous with respect to agricultural density, but not with respect to wheat density; and (2) agrophysical unit homogeneity test results indicating that with respect to agricultural density many agrophysical units are not homogeneous, but removal of one or more refined strata from any such current agrophysical unit can make the strata homogeneous. The apportioning procedure results indicated that the current procedure is not performing well and that the apportioned estimates of refined strata wheat area are often unreliable

    Large Area Crop Inventory Experiment (LACIE). Intensive test site assessment report

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    There are no author-identified significant results in this report

    Evidence for a non-genomic action of testosterone in skeletal muscle which may improve athletic performance: Implications for the female athlete

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    This review will focus on the proposed second mode of testosterone action (now termed non-genomic) that appears to occur independently of the traditional transcriptional mechanism in mammalian skeletal muscle cells which may enhance skeletal muscle contractile properties. This mechanism of testosterone action differs from the traditional pathway, originating at the cell membrane, having a rapid onset of action, requiring second messengers to execute its effects and is insensitive to inhibitors of traditional androgen receptor action, transcription and protein synthesis. Importantly, unlike the traditional action of testosterone in skeletal muscle, this non-genomic pathway is shown to have a direct acute effect on calcium-dependent components important for the contractile process. The changes within the contractile apparatus may enhance the ability of the muscle to produce explosive power during athletic performance. Rapid increases in Inositol triphosphate mass and calcium release from the sarcoplasmic reticulum have been reported in rodent skeletal muscle cells, and a rapid androgen (dihydrotestosterone)- induced increase in peak force production has been recorded in intact rodent skeletal muscle fibre bundles while showing increases in the activity of the Ras/MAP/ERK mediated pathway. Because the non-genomic action of testosterone is enhanced during increases in exposure to testosterone and is acute in its action, implications for athletic performance are likely greater in females than males due to natural fluctuations in circulating testosterone levels during the female menstrual cycle, reproductive pathology, and changes induced by hormonal contraceptive methods. Research should be undertaken in humans to confirm a pathway for non-genomic testosterone action in human skeletal muscle. Specifically, relationships between testosterone fluctuations and physiological changes within skeletal muscle cells and whole muscle exercise performance need to be examined

    A review of cricket fielding requirements

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    Cricket is played in three formats at elite level: Test, One Day and Twenty20. Fielding is an important component of cricket, as all players are obliged to field. However, there is a paucity of literature on fielding compared with that on batting and bowling. We review the available literature in terms of technical, mental, physiological and physical factors important to fielding, to identify knowledge gaps and better understand the performance requirements of fielding in cricket

    Effects of a six-week strength training programme on change of direction performance in youth team sport athletes

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    This study investigated the effects of eccentric phase-emphasis strength training (EPE) on unilateral strength and performance in 180- and 45-degree change of direction (COD) tasks in rugby union players. A 12-week cross-over design was used to compare the efficacy of resistance training executed with 3 s eccentric duration (EPE, n = 12) against conventional strength training, with no constraints on tempo (CON, n = 6). Players in each condition were categorised as ‘fast’ (FAST) or ‘slow’ (SLOW) using median trial times from baseline testing. Players recorded greater isometric strength improvements following EPE (ES = −0.54 to 1.80). Whilst these changes were not immediate, players improved in strength following cessation. Improvements in 180-degree COD performance was recorded at all test-points following EPE (ES = −1.32 to −0.15). Improvements in 45-degree COD performance were apparent for FAST following CON (ES = −0.96 to 0.10), but CON was deleterious for SLOW (ES = −0.60 to 1.53). Eccentric phase-emphasis strength training shows potential for sustained strength enhancement. Positive performance changes in COD tasks were category- and condition-specific. The data indicate the greatest improvement occurred at nine weeks following resistance training in these players. Performance benefits may also be specific to COD task, player category, and relative to emphasis on eccentric phase activity

    Tapering practices of New Zealand’s elite raw powerlifters

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    The major aim of this study was to determine tapering strategies of elite powerlifters. Eleven New Zealand powerlifters (28.4 ± 7.0 years, best Wilks score of 431.9 ± 43.9 points) classified as elite were interviewed, using semi-structured interviews, about their tapering strategies. Interviews were transcribed verbatim and content analyzed. Total training volume peaked 5.2 ± 1.7 weeks from competition while average training intensity (of 1RM) peaked 1.9 ± 0.8 weeks from competition. During tapering volume was reduced by 58.9 ± 8.4% while intensity was maintained (or slightly reduced) and the final weight training session was performed 3.7 ± 1.6 days out from competition. Participants generally stated that tapering was performed to achieve full recovery; that accessory work was removed around two weeks out from competition; and, deadlifting takes longer to recover from than other lifts. Typically participants stated that trial and error, and changes based on ‘feel’ were the sources of tapering strategies; equipment used and movements performed during tapering are the same as in competition; nutrition was manipulated during the taper (for weight cutting and/or performance aims); and, poor tapering occurred when too long (one week or more) was taken off training. These results suggest that athletes may benefit from continuing to strength train prior to important events with reduced volume and maintained intensity. Only exercises that directly assist sports performance should remain in the strength program during tapering, to assist with reductions in fatigue while maintaining/improving strength expression and performance

    The influence of different length between match microcycles on neuromuscular, hormonal and perceptual responses in professional rugby league players

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    Optimal recovery between matches is critically important in team sports. Indeed, altered neuromuscular performance, hormone levels and increased fatigue can manifest in under recovered team sport athletes. However, the recovery patterns in these variables in the days following professional rugby league matches is unknown. The purpose of this study was to examine the influence of different between-match training periods on neuromuscular, hormonal and perceptual measures in professional rugby league players. Following familiarization, 12 professional rugby league players from the same team were assessed for changes in countermovement jump (CMJ) (force, power, flight time), perceptual responses (fatigue, well being and muscle soreness) and salivary hormone (testosterone (T) and cortisol (C)) levels during 5, 7 and 9 day periods between matches. Measures were taken 4h prior to the initial match, and then 1, 2, 4, 6*, 7*, 8* and 9* days following (*depending on group). All training was prescribed by the coaches and monitored using the session-RPE method. Lower daily training load was completed on the 5-day compared with the 7 and 9-day conditions (p\u3c0.05). Some CMJ variables (flight time and flight time:contraction time), perception of fatigue, well-being and muscle soreness were reduced in the 2 days following the match in each condition (p\u3c0.05). All CMJ variables returned to near baseline values following 4 days in each condition. Both CMJ maximum and relative power were lower in the 7 day condition when compared with the 9 day condition (p\u3c0.05). Fatigue levels were reduced at 48 h in the 7 and 9-day groups (p\u3c0.05) but had returned to baseline in the 5-day group. All perceptual measures returned to baseline levels prior to the following match in each condition and followed changes in training load. Salivary T and C did not change in response to the match. These results show that neuromuscular performance and perception of fatigue are reduced for at least 48 h following a rugby league match but these can be fully recovered within 4 days. CMJ variables involving flight time appear to be best for assessing acute fatigue caused by a match, and variables involving power may be useful in assessing accumulated fatigue. The perceptual measures were sensitive to both acute fatigue and accumulated fatigue. The salivary hormone analyses were of limited value for assessing recovery. These findings show that with correct training, it is possible to recover neuromuscular, perceptual and endocrine measures within 4 days after a rugby league match

    Black Holes with a Massive Dilaton

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    The modifications of dilaton black holes which result when the dilaton acquires a mass are investigated. We derive some general constraints on the number of horizons of the black hole and argue that if the product of the black hole charge QQ and the dilaton mass mm satisfies Qm<O(1)Q m < O(1) then the black hole has only one horizon. We also argue that for Qm>O(1)Q m > O(1) there may exist solutions with three horizons and we discuss the causal structure of such solutions. We also investigate the possible structures of extremal solutions and the related problem of two-dimensional dilaton gravity with a massive dilaton.Comment: 36 pages with 5 figures (as uuencoded compressed tar file) (revised version has one major change in bound on mass for extremal solution and minor typos fixed), harvma
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